Exception 4 on mips bubblesort - mips

Question

So i have to write a bubblesort programm in mips using QtSpim for a class but i get an Exception 4 [Adress error in inst/data fetch]. I have searched in other topics and use the .align 2 directive before defining an array for 5 integers but it still isn't getting fixed.
Here's the code:
.text
.globl main
main:
la $t1, array #sets the base adress of the array to t1
la $a0, in_prompt
li $v0, 4
syscall
li $t2, 0 #init to 1
read_loop:
beq $t2, 5, read_key #break if t2 = 5
la $a0, num_prompt
li $v0, 4
syscall #"Give number"
#move $a0, $t2
#li $v0, 1
#syscall #current number to be read
li $v0, 5 #read int. 5 times
syscall
sw $v0, ($t1) #move input from v0 to the array
addi $t1, $t1, 4 #move t1 to the next position in the array
addi $t2, $t2, 1 #increment counter (t2) by 1
j read_loop
read_key:
la $a0, search_q
li $v0, 4
syscall #print query prompt
li $v0, 5
syscall
move $t3, $v0 #number we're looking for (KEY)
move $a0, $t1 #array to pass as arguement
jal bubblesort
move $a0, $v0 #move into a0 the sorted array
move $a1, $t3 #move the KEY into a1 as arguement
jal binarysearch
move $t1, $a0 #move into t1 the array
move $t0, $a1 #move into t0 the KEY
move $t3, $v0 #move into t3 the result of binarySearch
beq $t3, -1, not_found #if key was not found
move $a0, $t0
li $v0, 1
syscall
la $a0, found_pr
li $v0, 4
syscall
j print_array
not_found:
move $a0, $t0
li $v0, 1
syscall
la $a0, not_found_pr
li $v0, 4
syscall
j print_array
print_array:
li $t2, 1 #init to 1
print_loop:
beq $t2, 5, EXIT
lw $a0, ($t1)
li $v0, 1
syscall
addi $t1, $t1, 4
addi $t2, $t2, 1
j print_loop
EXIT:
li $v0, 10
syscall
##############binarysearch#################
binarysearch:
addi $sp, $sp, -24 #reserve space for 6 elements
sw $a0, 0($sp) #push a0 (array)into stack
sw $a1, 4($sp) #push a1(KEY) into stack
sw $s0, 8($sp) #push s0
sw $s1, 12($sp) #push s1
sw $s2, 16($sp) #push s2
sw $ra, 20($sp) #push ra
sw $s3, 24($sp) #push s3
li $s0, 0 #low = 0
li $s1, 4 #high = 4
while:
bgt $s0, $s1, exit_search #if low > high branch
move $a1, $s0 #move into a1 low
move $a2, $s1 #move into a2 high
jal calc_middle #jump to calc_middle
move $s2, $v0 #move into s2 the return value of calc_middle
lw $a0, 0($sp) #restore into a0 the 1st stack el(array)
lw $a1, 4($sp) #restore into a1 the 2nd stack el(KEY)
add $a0, $a0, $s2 #move the array to middle
lw $s3, ($a0) #load into s3 the a[middle]
beq $a1, $s3, exit_search_found #break if KEY == a[middle]
blt $a1, $s3, less_t_middle #if the key is less than the middle element
addi $s0, $s2, 1 #if the key is greater than the middle element set new low
j while
less_t_middle:
addi $s1, $s2, -1 #new high
j while
exit_search_found:
move $v0, $s2 #return found
lw $s0, 8($sp)
lw $s1, 12($sp)
lw $s2, 16($sp)
lw $ra, 20($sp)
addi $sp, $sp, 24
jr $ra
exit_search:
li $v0, -1 #return -1
lw $s0, 8($sp)
lw $s1, 12($sp)
lw $s2, 16($sp)
lw $ra, 20($sp)
addi $sp, $sp, 24
jr $ra
##############calc_middle##################
calc_middle:
add $a1, $a1, $a2
sra $a1, $a1, 1
move $v0, $a1
jr $ra
##############bubblesort###################
bubblesort:
addi $sp, $sp, -12
sw $s0, 0($sp)
sw $s1, 4($sp)
sw $s2, 8($sp)
li $s2, 4 #j = 5
li $s1, 0 #i = 0
outer_loop:
addi $s2, $s2, -1 #i = j - 1
blt $s2, $zero, exit_sort
inner_loop:
bgt $s1, $s2, outer_loop #if i > j - 1
lw $s3, 0($a0) #load into s3 the a[i]
lw $s4, 4($a0) #load into s4 the a[i+1]
bgt $s3, $s4, swap #if a[i] > a[i+1]
addi $s1, $s1, 1 #i++
j inner_loop
swap: move $s0, $s3 #tmp = a[i]
move $s3, $s4 #a[i] = a[i+1]
move $s4, $s0 #a[i+1] = tmp
addi $a0, $a0, 4 #point to the next element ????
addi $s1, $s1, 1 #i++
j inner_loop
exit_sort:
lw $s0, 0($sp)
lw $s1, 4($sp)
lw $s2, 8($sp)
addi $sp, $sp, 8
move $v0, $a0 #pass into v0 the sorted array
jr $ra
.data
.align 2
array: .space 20
in_prompt: .asciiz "Enter 5 numbers:\n"
num_prompt: .asciiz "Give number: "
search_q: .asciiz "what are you looking for?\n"
not_found_pr: .asciiz " not found in array: \n"
found_pr: .asciiz " found in array: \n"